The influence of fine particles composition on optimal ... · Markestad and Christie 1996),...
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ORIGINAL PAPER - PRODUCTION ENGINEERING
The influence of fine particles composition on optimal designof sand control in offshore oilfield
Fucheng Deng • Jingen Deng • Wei Yan •
Haiyan Zhu • Lan Huang • Zijian Chen
Received: 6 September 2012 / Accepted: 2 December 2012 / Published online: 20 April 2013
� The Author(s) 2013. This article is published with open access at Springerlink.com
Abstract The fine particles have significant influence for
sand control mode selection. According to investigation and
analysis, we learn that the gravel packing has been used
widespread in sand control when the contents of fine par-
ticles are high. Based on designing the pre-packed screen,
different fine particles sand control research is completed
combining with test method. (1) We find that the sequence
of fine particles flowing into the well has an enormous
impact on the screen jam rate, and the smaller the fine
particle diameter, the more obvious the screen plugging.
The jam rate for the pure clay is five times with pure fine-
silty sand, and four times with mixture of the fine-silty sand
and the clay. When the experimental achieve octet stability,
the Fluid Productivity Index Per-Meter (FPIPM) of the pure
clay is pretty much equivalent with the mixture of the fine-
silty sand and the clay. It is 70 % of the pure fine-silty sand
FPIPM but has limited influence to effectiveness of the
blockage. (2) Sand control selection in the offshore oilfield
suggests the gravel packing will be applied when the fine
particles content is over 5 %. Compared to this select range,
it is conservative and experiments show that the fine par-
ticles content achieves 100 %, the pre-packed screen also
can cope with sand control effectively. When comparing
with experimental result about the gravel packing sand
control under the same condition, the both FPIPM in steady
is same. So, it is more suitable to be widely used combined
with the production cost.
Keywords Pre-packed screen � Gravel packing �Fine particles � Sand control design � FPIPM
Introduction
There is a lot of research on the blueprint of sand control
(Bennett et al. 1998; Farrow et al. 2004; McCarthy and
Mickelburgh 2010; Schwartz 1969; Slayter et al. 2008).
But the gravel packing is used in concert with other screen
in oil field which is fit for the formation of high fine par-
ticles content. Such as, Tiffin (Tiffin et al. 1998, 2003)
introduced two new parameters in sand control with the
sand particle size distribution: sorting characteristics
(SC = d10/d95) and fine particles (the quality percentage
of \45 lm particles), and the gravel packing completion
was used in the formation of high fine particles content.
Mohamad et al. (2008) published an article in the JPT
which showed fine particles (\45 lm) content with 35 %.
The gravel packing was used in the initial stage, and it
found that the skin was very high under this way. There-
fore, wire-wrapped screens were used in some part of
wells, but the production differential pressure should be
accurately restricted. Field A and B, which the grain dis-
tribution are SC \ 10 and UC \ 3, and the fine particles
contents are greater than 5 %. For the formation is weak
cementation, field A applied high quality screen indepen-
dent in producing for many years. But the sand production
is very high.
Because of the complication and risk in the deep water
environment, gravel pack completion is used in the
development of most of the deep water oil and gas fields.
And the water injection well use the casing perforation,
wire wrapped screen and high quality screen. Based on
Tiffin method and Bennett method (Leo et al. 2002;
Markestad and Christie 1996), Schlumberger company
summarizes well open hole completion sand control design
method of the offshore horizontal according to the imple-
mentation experiences of four field completion engineers,
F. Deng (&) � J. Deng � W. Yan � H. Zhu � L. Huang � Z. Chen
State Key Laboratory of Petroleum Resource and Prospecting,
China University of Petroleum, Beijing 102249, China
e-mail: [email protected]
123
J Petrol Explor Prod Technol (2013) 3:111–118
DOI 10.1007/s13202-012-0045-7
as described below: (1) no matter deep or shallow water,
when the well design lifetime is longer than the time of
pore pressure failure in rocks that causes rock particles
stress to increase, the gravel packing completion can be
used in sand control. (2) When the water depth is over
1500 ft (457 m), gravel packing completion can be all
applied to both injection wells and production wells. (3)
When the water depth is less 1500 ft, d50 \ 75 lm (very
fine siltstone reservoir), both injection wells and production
wells, no matter how heterogeneity of the reservoir con-
ditions does, gravel packing completion can be accepted.
(d50 [ 75 lm: UC [ 5, SC [ 10 and fine siltstone [ 5.
The fine particles can be divided into fine-silty sand
(d50 = 38 lm) and clay (d50 = 2 lm) (Ballard et al.
2008; Byrne and Waggoner 2009; Byrne et al. 2009, 2010).
After investigation we found that there are only few studies
of different fine particles composition on the effect of the
sand control. Through the analysis of various oilfield for-
mation data, we realized that the fine particle is more or
less exists in the formation. As we know, the cost of gravel
packing is several times higher than independent high
quality screen, if the well completion is prevalent in gravel
packing, this will increase not only the operation time, but
also the cost of well completion. As we all know, the pre-
packed screen is also one of many options of sand control
methods. Based on the pre-packed screen design and
numerous laboratory experiments, this paper is emphasis
on the effects of the fine particle to jam the pre-packed
screen.
Introduction to gravel pre-packed screen
There are three parts in pre-packed screen: the outer pro-
tective layer, the packing filtering layer and the base pipe.
Since the wire wrap screen (WWS), mesh screen (MS) and
slotted screen are less sensitive to shale content, especially
the WWS and slotted screen, they are suitable to cooperate
with the pre-packed gravel. Moreover, due to the low cost of
slotted screen and WWS, this paper was working on a ladder-
shaped opening model to fit the outer protective layer, with
a = 0.3 mm accuracy, and every wire is welded to form an
entity by metal bars. As for the base pipe, we prefer network,
and the base pipe is distributed with flowing holes. In order to
prevent the gravel pre-packed falling from the screen under
certain pressure, the mesh monolayer with 0.3 mm gap width
is outside of the base pipe. Considered the influence of the
screen weight operate to the process, we chose the stainless
steel which is more flexible in elasticity and lighter in weight
as the wire wrapped protective layer outside the screen and
the inner base pipe. And there are flowing holes on the steel in
order to make the formation fluid flow more smoothly. In this
paper, the packing thickness of the pre-packed screen is
20 mm, the size of the gravel is 20–40 mesh, and the length
of the screen is 35 cm. The schematic diagram (left) and the
physical map (right) are shown in Fig. 1.
Introduction to the experiment
The former researches of sand control screen performance
are all based on some single units of sand control, for small
size of this kind of simulating experiments there is a huge
different between lab conditions and real production. In this
case, the author did a series of comparative evaluation
experiments using the simulative experiment device of oil
well sand control (Wang et al. 2011; Zou et al. 2009) in
China University of Petroleum (Beijing). This set of
experiment device can do the evaluating experiment of
wellbore oil and sand radius flow regulations under
Fig. 1 Sketch of gravel pre-
packing screen
112 J Petrol Explor Prod Technol (2013) 3:111–118
123
confining pressure and can do better evaluation of screen
performance from the integral view, because it’s under-
taking with a full-size sand control pipe and simulates stable
reservoir producing conditions using diaphragm pump,
safety valve and a series of devices. During the experiment,
we can analyze how oil production rate and sand production
rate change with time by measuring the flow rate, pressure
and sand production rate and other parameters.
Device for experiment
This set of device including five parts: oil and sand mixing
system, pressure and liquid supply circulation system, sand
producing simulation device, oil and sand simulation sys-
tem, data auto-acquisition system (Fig. 2).
Sand control experiment process
(1) After setting and debugging the equipment, we inject
some white oil. Make sure the oil is flowing from all the
entrance holes and check the pressure testing system. (2)
Trice up the pre-packed screen and put it in the pressure
vessel, lay a rubber cushion as seal ring on the top of the
vessel, then padlock the pressure vessel cap. (3) Mix different
sands according to experiment demand, and add clay to the
sand in a certain ratio, then pour the white oil, mixed sand and
clay into the oil-sand blending tank in a certain ratio. (4) Rig
up circulation system pipeline, pressure sensor of the import
and export, filter of sand produced, data acquisition card, and
set pump pressure according to the formation pressure. (5)
Turn on computer data detection and acquisition system to
record the pressure and flow rate of every point in real-time
during the experiment. (6) Separate the sand from oil using
the shaker, clean the sand produced using kerosene and weigh
the sand, then analyze the sand using laser grain-size analysis.
(7) Repeat the above procedures until the end of the experi-
ment. Finally clean the device.
Optimization principles
In order to evaluate the performance of the pre-packed
screen in the simulative production process, and also in
oilfield production practice, finding a sand control method
which is suitable for long-term development in offshore
oilfield and balance the contradiction between sand control
and production, propose the principle that we should
improve productivity as much as possible under the guar-
antee of sand control efficiency, so we need to compare the
change rules of sand production and productivity under
different sand control methods, then we can optimize the
packing way of pre-packed screen based on the above
principle. The sand production we use here is the sand
collected in each experiment, and combined with oil vol-
ume produced we can calculate the sand concentration.
Production is measured by the metric fluid productivity
index (Wan 2000), shown in formula (1).
J ¼ Q
ðpe � pwfÞhð1Þ
where: J—fluid productivity index per meter (FPIPM),
m3/(m 9 d 9 MPa); q—flow rate, m3/d; h—effective
Fig. 2 Set-up diagram of oil
well sand control screen
evaluation experiment.
1 containers; 2 high-pressure
pump; 3, 8 pressure sensor;
4 flowmeter; 5 safety valve,
6 autoclave; 7 deceleration
check valve; 9 oil and sand
separator; 10 oil sands cleaner;
11 data acquisition card
J Petrol Explor Prod Technol (2013) 3:111–118 113
123
overflow length of the screen, m; Pe—reservoir pressure,
MPa; Pwf—bottom hole gas flowing pressure, MPa.
Comparative experiment research of different fine
particles
The influence of sand production sequence to screen
about the experimental results and analysis
Since the clay can plug the pore of the screen and reduce
production in the late period, clay content is crucial to the
selection of sand control methods in the design process.
Considering the shale content limit, when shale content is
very high, we assumed that there is only clay existed
during the production. Therefore, we performed the anti-
plugging of the screen under the conditions of the relative
content of clay to liquid production (90 % of smectite). In
the test, 5 kg clay is mixed in test oil, at this time the clay
content is 2 % (the comparing of clay and the test oil).
Through the observation of the oil color in the oil-out, the
oil is yellow in the initial period for containing a certain
amount of clay. In 20 min, the oil gradually change to
limpid. When the flow regime tend is stable, 4 kg clay is
mixed into the blending tank, this time the clay concen-
tration reaches 4 %. In the initial 3 min the oil color shown
a yellowish, then turn to clear again. After the flow regime
is in stable, 5.77 kg fine-silty sand (standard industrial
160–200 mesh) is mixed into the blending tank, the flow
fall subsequently. Figure 3 shows initial data of production
rate and pressure with pure clay.
As is shown in Fig. 4, we found that the mud cake
separated some distinct layers. The inner layer of the mud
cake which adjoins by the screen is fine and smooth with
clay. The out layer of the mud cake is coarser than the inner
layer, for its apparently fully fine-silty sand component. It
shows that a layer of mud cake will be firstly attached on
the screen during the experiment. Then the added clay and
fine-silty sand adhere onto the previous layer and gradually
accumulate more mud cake. The thickness of mud cake
increases with the adding speed of clay and fine-silty sand,
and the flow rate slow down gradually at the same time.
During the productive process of production well, the
weakly consolidated sands produce tiniest particles of clay
at first and then free sand. When the productive velocity
reaches a particular level, the formation suddenly produces a
huge amount of sand. The whole experimental simulation is
the same as the real sand production in the process of pro-
duction wells, and the sand control design focuses on pre-
venting free sand into the productive pipelines that cause the
productive pipeline to be erosive. According to the experi-
mental results, the pre-packed screen can block these clay
and free sand outside the screen, gradually they accumulate
a layer of mud cake commendably. When making a selec-
tion of sang control, especially to those deep-water oilfields
(depth over 1500 ft), the field staff always tend to select the
gravel packing. However, this method is relatively conser-
vative, which increase both the operational time and the cost
of well completion. Therefore, expanding the optimal
principles of sand controlling should be considered, espe-
cially about select range of fine-silty sand. Screens can be
used for 5 years, and introducing the pre-packed screen to
replace the gravel packing will be an effective improvement
after considering the formation characteristic.
The experiment result of the pure fine-silty sand
The fine particles (\45 lm) are very important on jamming
the screen. In order to find the theory of plugging mechanism
of the pre-packed screen, the fine-silty sand with standard
industrial 160–200 mesh is applied in simulation experi-
ment, and the sand content is 6 %. Figure 5 shows initial data
of production rate and pressure with pure fine-silty sand.
Obviously, from the figure that, in the initial production
stage, the flow rates is very high, but they also decline rapidly
with the blockage of the screen. Especially, ten minutes at the
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 50 100 150 200
Time(min)
Flow
Rat
e(kg
/s)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Pres
sure
(MPa
)
Flow Rate
Pressure
Clay 5kg Clay 4kgfine-silty sand
5.77kg
Fig. 3 Initial data of
production rate and pressure
with pure clay
114 J Petrol Explor Prod Technol (2013) 3:111–118
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beginning of the experiment, the production flow down close
to 70 % with initial. It means that the fine-silty sand has
dramatically effective clog for the screen in the producing
time, also reduces the production by a wide margin.
In the test, there are 15 kg fine-silty sand content and
3 % the oil sand ratio. In the first 5 min of the experiment,
relatively turbid oil is flushing out. It tells us the production
is high, and the sand content is also high. With the pro-
duction gradually reduces, the oil become transparent, and
the FPIPM reaches stability. As is shown in Fig. 6, the
color of the mud cake is the original colors of the fine-silty
sand for no clay mixed.
The experiment result of the mixture of the fine-silty
sand and clay
In order to clarify the sand control effect of the clay content
for the pre-packed screen, in the same experimental condi-
tions, the tests of the mixture of the fine-silty sand and clay
are mixed with the sand content of 6 %, and the clay content
of 10 %. In the early of the test, it will be mixed into the oil.
Figure 7 tells us how the overflow rate and producing
pressure drop changes with time using pre-packed screen of
the mixture of the fine-silty sand and clay. From the graph, it is
obviously show us that the flow rates of all the three are very
high in the initial production stage, but they also decline very
soon with the blockage of the screen, then the liquid produc-
tion achieves initial stabilization along with production.
Comparative analysis with different fine particles
Obviously, from Fig. 8 that the FPIPM declines fast with
content of the clay, and the higher the clay content is, the
faster the screen is jammed. The jam rate for the pure clay
is 5 times with pure fine-silty sand. The jam rate for the
mixture of the fine-silty sand and clay is 25 % higher than
the pure fine-silty sand. According to this jamming result,
during the whole process of sand production, the sequences
of clay and fine-silty sand enter into screens has no dif-
ference from final jamming effect but the time in jamming
process. Thus, in the productive process, it is necessary to
control producing pressure, which can raise the effective
previous permeability of screens as well as reduce the
proportion of clay in oil, and increase prophase production.
Figure 9 shows us that the test in the stability on mixing
the clay is significant influence with the FPIPM. The FPIPM
Fig. 4 Cross-section diagram of the mixture of the clay and fine-silty sand
0
0.05
0.1
0.15
0.2
0.25
0 20 40 60 80 100
Time(min)
Flow
Rat
e(kg
/s)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Pres
sure
(MPa
)
Flow RatePressure
Fig. 5 Initial data of
production rate and pressure
with pure fine-silty sand
J Petrol Explor Prod Technol (2013) 3:111–118 115
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of the mixture of the fine-silty sand and clay declines 30 %
comparing to the pure fine-silty sand. The FPIPM in stable
of the pure clay declines 35.7 % relative to the pure fine-
silty sand. And the FPIPM in stable of mixture of the fine-
silty sand and clay is 9 % higher than pure clay. For the same
pre-packed screen, the smaller the grain size of the fine
particles is, the better effect on the sand control is jammed.
And the fine particles can reduce the production directly.
This phenomenon is convinced that jamming capacity of
clay is greater than fine-silty sand. The higher the content of
clay is, the stronger plugging ability to screen is.
Comparative analysis with gravel packing sand control
To establish a high quality screen and 30 mm thickness
with 20–40 mesh gravel packing layer sand control model,
and it is also applied the same fine-silty sand and clay
experiment simulating conditions. The specific data with
the test is as follows:
It is noticeable from Fig. 10 that the FPIPM of the pre-
packed screen in the whole production stages is almost
equivalent with the gravel packing sand control. It shows
that two sand control methods have the same effect for fine
particles. If the pre-packed screen is used in the sand
control process, it has a great impact and save a large
number of operation time and cost. In selecting process of
sand control in offshore oilfield, Tiffin had suggested that
the gravel packing could be applied to well completion
when the content of fine particles is over 5 %. This range is
relatively conservative. Through several experiments, pre-
packed screen can prevent sand control effectively when
the content of fine particles reaches to 100 %. That means,
to a certain extent, pre-packed screen can replace the gravel
packing in most areas, and the new solution will save both
operational time and production expenses.
Conclusions
1. The sand control comparative experiment in different
fine particles of pre-packed screen was built to study.
From these simulation analysis, we found that the fine
particles (\45 lm) have strongly blocking to the well
Fig. 6 Post-experiment mud cake of pure fine-silty sand
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0 20 40 60 80 100 120
Time(min)
Flow
Rat
e(kg
/s)
0
0.5
1
1.5
2
2.5
3
3.5
Pres
sure
(MPa
)
Flow Rate
Pressure
Fig. 7 Initial data of
production rate and pressure
with mixture of the fine-silty
sand and clay
116 J Petrol Explor Prod Technol (2013) 3:111–118
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production. Especially the smaller the fine particles
diameter is, the more obvious effect the screen
blockage is. From the comparison of the different fine
particles composition, the jam rate for the pure clay is
five times with pure fine-silty sand, and four times with
mixture of the fine-silty sand and the clay. When the
experiment achieve octet stability, the FPIPM of the
pure clay is pretty much equivalent with the mixture of
the fine-silty sand and the clay, it declines 30 % with
the pure fine-silty sand.
2. From the experiment, it is similar between the mixture
of the fine-silty sand and clay experiment result with
adding the clay in first and the fine-silty sand in
second. It shows that the produce order of different
fine particles seem to make any difference to jam the
pre-packed screen. But the mud cake has some
0
10
20
30
40
50
60
70
80
90
0 20 40 60 80 100 120 140 160
Time(min)
FPIP
M(m
3 /d×
m×
MPa
)
Pure Fine-silty Sand
Mixture of the Fine-silty Sand and Clay
Pure Clay
Fig. 8 FPIPM comparative
diagram of different fine
particles
0
2
4
6
8
10
12
14
16
Pure Fine-silty Sand Mixture of the Fine-silty Sandand Clay
Pure Clay
FPIP
M in
Sta
ble(
m3 /d
×m
×M
Pa)Fig. 9 FPIPM in stable
comparative diagram of
different fine particles
0
10
20
30
40
50
60
70
0 20 40 60 80 100 120 140
Time(min)
FPIP
M(m
3 /d×
m×
MPa
)
Pre-packed Screen
Gravel Packing Sand Control
Fig. 10 FPIPM comparative
diagram of the pre-packed
screen and gravel packing sand
control
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different, it will be discovered that the mud cake has
obvious separated layer, when the sanding has a
certain order.
3. Whether in deep-water oilfields or offshore oilfields, in
the choice of the sand control design former engineers
had used gravel packing to make well completion when
the content of fine particles is over 5 %. This range is
relatively conservative. Through several experiments, a
new study has shown that pre-packed screen can
accomplish the sand control effectively when the
content of fine particles reaches 100 %. Compared
with pre-packed screen and the gravel packing, the
FPIPM is all the same. Whether from operation or
economically, the formation with high fine particles,
the pre-packed screen is more suitable for widely used.
Acknowledgments This paper was supported by the Program for
National Science and Technology Major Project of the Ministry of
Science and Technology of China (2011ZX05024-003-02).
Open Access This article is distributed under the terms of the
Creative Commons Attribution License which permits any use, dis-
tribution, and reproduction in any medium, provided the original
author(s) and the source are credited.
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